Power supplies are typically used to convert alternating current (AC) power to direct current (DC) power, and to convert DC power to AC power for different purposes. Power (voltage, current) obtained on output terminals is to meet requirements of a load consuming this output power (voltage, current).
Different power supplies are known in the art. For instance, as described in Ser. No. 08/032,132, now U.S. Pat. No. 5,352,931 and Ser. No. 08/032,131, both invented by the same inventive entity as the present invention, the power supply includes a plurality of identical battery units interconnected by respective switch units. Each switch unit is controlled by a central control unit in order to re-arrange the battery units in series and/or parallel arrangement and to obtain a desired step voltage on the output terminals of the power supply.
It would be highly desirable to provide a power supply with polarity exchange function and AC frequency control, and also the power supply where the step voltage could be linearized or PWM controlled.